Dv. Cao et al., Self-diffusivities of N-2, CH4, and Kr on 4A zeolite pellets by isotope exchange technique, J PHYS CH B, 104(45), 2000, pp. 10498-10501
The isotope exchange technique (IET) was used to measure equilibria and kin
etics for adsorption of pure N-2, CH4, and Kr on a 4A zeolite sample. The i
ntracrystalline self-diffusivities for these gases were measured under trul
y isothermal conditions. The self-diffusivities of Kr and CH4 were smaller
than that of N-2 by 2 and 1 order of magnitude, respectively. The self-diff
usivity of N-2 was independent of its surface coverage but the self-diffusi
vities of CIC and Kr increased with increasing coverages in the high-pressu
re region. This effect was much more pronounced for Kr. The activation ener
gies for self-diffusion of the gases increased in the order Kr > CH4 > N-2
while the isosteric heats of adsorption of these gases in the Henry's law r
egion were very close. The activation energies were larger than the corresp
onding isosteric heats of adsorption for each gas.